Process for preparing a body having an osseointegrative topography formed on its surface

Abstract

A process for preparing a body having an osseointegrative topography formed on its surface. The process includes the steps of providing a primary body made of a titanium-zirconium alloy containing 13 to 17 wt-% of zirconium, sandblasting the primary body, and etching the sandblasted primary body with an etching solution including hydrochloric acid, sulfuric acid and water at a temperature of above 80 C. to obtain the body, said etching being performed for a duration of 350 seconds at least.

Claims

1. A process for preparing a body having an osseointegrative topography formed on its surface, the process comprising: a) providing a primary body made of a titanium-zirconium alloy containing 13 to 17 wt-% of zirconium, b) sandblasting the primary body, and c) etching the sandblasted primary body with an etching solution comprising hydrochloric acid, sulfuric acid and water at a temperature of above 80 C. for a duration in a range of from 350 to 540 seconds to obtain the body.

2. The process according to claim 1, wherein the etching is performed for a duration in a range of from 360 to 480 seconds.

3. The process according to claim 1, wherein at least in a region directly adjacent to the surface, the alloy is essentially in the alpha-phase.

4. The process according to claim 1, wherein in step b) Al.sub.2O.sub.3 particles having an average particle size in a range from 0.1 mm to 0.6 mm are used as sandblasting material.

5. The process according to claim 1, wherein the topography is defined by at least one of the following parameters: i) an arithmetic mean deviation of the surface (S.sub.a) in three dimensions in a range of from 0.1 m to 2.0 m; ii) a maximum peak to valley height of the profile (S.sub.r) in three dimensions in a range of from 1.0 m to 20.0 m; iii) a skewness of the profile (S.sub.sk) in three dimensions in a range of from 0.6 to 0.6; and iv) a developed surface area (Sdr) in a range of from 15% to 25%.

6. The process according to claim 1, wherein an amount of zirconium contained in the alloy is in a range of from 13 to 15 wt-%.

7. The process according to claim 1, wherein the alloy contains iron in an amount higher than 0.001 wt-%.

8. The process according to claim 1, wherein the alloy contains an amount of iron less than 0.05 wt-%.

9. The process according to claim 1, wherein the alloy contains less than 0.1 wt.-% hafnium.

10. The process according to claim 1, wherein after step b) and prior to step c) the sandblasted primary body is treated with a pickling solution comprising hydrofluoric acid and nitric acid, whereby a native oxide layer formed on the titanium-zirconium alloy is at least partially removed.

11. The process according to claim 1, wherein the temperature of the etching solution during the entire etching is higher than 80 C.

12. The process according to claim 1, wherein the sandblasted primary body is pre-heated to a temperature above room temperature immediately prior to step c).

13. The process according to claim 1, wherein the etching is performed for a duration in a range of from 360 seconds to 420 seconds.

14. The process according to claim 1, wherein in step b) Al.sub.2O.sub.3 particles having an average particle size in a range of from 0.15 mm to 0.5 mm are used as sandblasting material.

15. The process according to claim 1, wherein in step b) Al.sub.2O.sub.3 particles having an average particle size in a range of from 0.2 mm to 0.4 mm are used as sandblasting material.

16. The process according to claim 1, wherein the topography is defined by at least one of the following parameters: i) an arithmetic mean deviation of the surface (S.sub.a) in three dimensions in a range of from 0.4 m to 1.8 m; ii) a maximum peak to valley height of the profile (S.sub.r) in three dimensions in a range of from 3.0 m to 18.0 m; and iii) a skewness of the profile (S.sub.sk) in three dimensions in a range of from 0.4 to 0.6.

17. The process according to claim 1, wherein the alloy contains iron in an amount higher than 0.005 wt-%.

Description

EXAMPLES

(1) The present invention is further illustrated by way of the following working examples.

(2) Dental implants of a titanium-zirconium alloy containing 13 to 17 wt-% of zirconium were subjected to a sandblasting step followed by an etching step.

(3) The sandblasting step was performed by using Al.sub.2O.sub.3 (corundum) particles as sandblasting material.

(4) For the etching, the samples have been immersed in an etching bath comprising hydrochloric acid, sulfuric acid and water (the ratio of HCl (32%), H.sub.2SO.sub.4 (95%) and H.sub.2O being 2:1:1).

(5) Immersion was performed for 360 seconds, before the samples were rinsed with deionized water and kept in aqueous solution for further storage.

(6) Surface Topography

(7) The surface topography obtained by the above treatment and its similarity to the surface topography of the well-established SLA titanium body is illustrated by the figures, of which:

(8) FIG. 1 shows an SEM picture of the surface of the body treated according to the present invention with a scale relating to 10 micrometer being contained in the bottom left corner; and

(9) FIG. 2 shows an SEM picture of the surface of an SLA titanium body (for comparative reasons).

(10) As can be seen from the figures, the sample according to the present invention shown in FIG. 1 exhibits a surface topography which very closely resembles the one of the known and established SLA surface on titanium, shown in FIG. 2.

(11) Residual Amount of Sandblasting Material

(12) Further samples were analysed using energy dispersive X-ray analysis (EDX) for measuring the residual amount of sandblasting material remaining on the surface after the etching step.

(13) In the framework of the EDX experiments, a first set of samples (samples 1) were acid etched using the etching bath mentioned above for 360 seconds, whereas a further sample (sample 2) was etched using the same etching bath, but for 300 seconds (for comparative reasons).

(14) For the sandblasting, two batches of corundum differing in the particle size distribution and the average particle size were used: for a first sub-set of samples 1 (sample 1.1), sandblasting was performed by using corundum particles, 85% of which having a particle size from 0.21 to 0.355 mm, the average particle size thus being in a range from 0.2 mm to 0.4 mm (sand A), while for a second sub-set of samples 1 (sample 1.2) and comparative sample 2, sand comprising corundum having a larger average particle size than sand A (sand B) was used as sandblasting material.

(15) The treatment thus led to three samples (samples 1.1, 1.2, and 2) summarized in Table 1 below:

(16) TABLE-US-00001 TABLE 1 Sample No. 1.1 1.2 2 (comparative) Etching 360 seconds 360 seconds 300 seconds duration Sandblasting Sand A Sand B Sand B material

(17) The Al contents (wt %) detected by EDX are presented in Table 2.

(18) TABLE-US-00002 TABLE 2 Sample No. 1.1 1.2 2.2 Al (wt %) 0.1 0.5 1.3

(19) As can be seen from Table 2, a significant decrease in the Al content (indicative of the amount of corundum particles sticking on the surface) was revealed for samples 1.1 and 1.2 in comparison to the comparative sample 2.

(20) As also shown in Table 2, a further decrease in the Al content and, therefore, of the residual corundum sticking to the surface was revealed for sample 1.1 that has been sandblasted with sand A having an average particle size in the range of 0.2 mm to 0.4 mm in comparison to sand B having a larger average particle size than sand A (sample 1.2).